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motor giving problems

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martin cropper23/07/2014 09:43:33
9 forum posts

hi to every one great site and some great stuff

my problem if any one can help

i have a brooke crompton 1hp motor

on an ixl lathe it was a replacement when i switch the motor on it runs beautiful no noise very quiate but when i connect it up to the lathe ie put belts on

it blows the 13 amp fuse

i put a little bit thicker wire in the fuse and it starts ok made it about 16amp

dose it need a starter switch or simler as its on a plug

thanks martin

Emgee23/07/2014 16:37:26
2312 forum posts
277 photos

Hi Martin

Seems the problem is starting current, this will be several times the run current for a brief period until the lathe gets up to speed. If you have put 15Amp fuse wire across the blown cartridge fuse remember the wire will take up to 32A to rupture, the flash when rupturing will produce a lot of heat so be careful.

You most likely need a dedicated 16A circuit wired to an isolator and motor starter, this way you will have a means of isolation, no-volt protection and with the correct overload fitted protection against motor overload.

Rgds, Emgee

martin cropper23/07/2014 17:56:48
9 forum posts

thanks emgee

i only tryed it with bigger fuse as dident want to damage anything till i got advice

my main feed is to 32 amp breaker thats why i tryed bigger fuse wire

so if i take the plug off an put to a dol starter switch or other it should be ok

thanks martin

Bob Brown 123/07/2014 18:48:29
1021 forum posts
127 photos

I run my machines with a starter even if they will run off a 13amp plug as it is a lot easier to turn on and off with the protection of a thermal overload relay. In your case 1hp needs a 2.8 to 4.2 amp overload set to around 3.2amps.

They are available from Toolstation amongst others

martin cropper23/07/2014 21:50:01
9 forum posts

thanks i will get one and fit it before i use it

thanks martin

Peter G. Shaw24/07/2014 13:46:28
1360 forum posts
44 photos


Just a thought. When you start it on the lathe in full working mode, you are adding load to the motor. This, in turn, will make it more difficult for the motor to run up to speed and this will cause the motor to take more current. I don't know this lathe, so this question may be somewhat pointless, but by any chance does the lathe have a clutch? If so, is it fully disengaged when you start the motor as, just as in a car, if it is engaged, then this will increase the load on the motor.

Also, some people who have a lever operated belt tensioner, have been known to use that as a pseudo-clutch.

Finally, a starter won't stop any overload from being passed onto the mains supply. Well, it will, actually, by virtue of causing the starter to trip out and disconnect the power to the motor, but then you could be in an even worse situation where the motor never gets up to speed.

It is my understanding that the purpose of a standard starter incorporating a no-volt release and thermal overload is that the thermal overload is to protect the motor against fire or burnout in the situation where it is stalled. The thermal overload has a short delay in it (bi-metalic strip overwound by a small heating coil) which should be sufficient to allow the high initial starting current to diminish to normal levels without tripping. What this means is that if the thermal overload is sized correctly, it WILL NOT stop the high starting current from being passed back to the mains supply.

I fear that a starter will not cure your problem. Unless, and this something I know very little about, it incorporates some sort of slow or soft start by limiting the amount of initial starting current. Suffice to say that my lathe starter has no such device.


Peter G. Shaw

Peter G. Shaw24/07/2014 15:11:37
1360 forum posts
44 photos

I should have added that I think a starter is a good idea anyway, but as you will realise, not for this particular problem.


Peter G. Shaw

martin cropper24/07/2014 20:31:26
9 forum posts

thanks peter

and every one else

i had a look inside to day an found the centrifugle weights were stuck open

but will put a switch on first before running her

thanks everone again for your advice owt machanical i can do but a loss with electrics

Phil Whitley24/07/2014 20:47:09
1394 forum posts
147 photos

Whoaa there lads! A 1hp motor will draw more than its rated current on starting, but should not draw anywhere near enough to blow a 13a fuse. There is something wrong here! Are you starting the motor on load IE turning the lathe gearbox all the way to the chuck? If you are you either need a bigger motor, or you need to start the motor, then put the load on using a clutch or jockey pulley. Is the motor single phase? does it have a capacitor to start it? Can you send a pic of the set up. Roughly speaking, 1hp=746 watts=3.1 amps on 240Volts, you would expect a surge of maybe 6 to 8 amps on start up, but no way should it clear a 13A cartridge fuse. My clarke compressor blows a fuse on odd occasions if the unloader valve fails, but it is 3hp, so right at the limit of a 13A fuse anyway. Incidentally, fusing factor for a 15A fuse wire is about 1.5 times the rated current, so a 15 amp wire should blow instantly at 22.5 amps, not 32A. Hope this helps, More info will help to sort this problem.


Phil Whitley24/07/2014 20:49:11
1394 forum posts
147 photos

OK, just got the last post and see it was stuck bob weights on the CF switch! that explains it!!

martin cropper24/07/2014 21:58:19
9 forum posts

thanks phil freed up welght and running ok with out load but still dose it under load must be somthing else

will try post a photo it is a i xi l lathe the same as the one on lathes

screw cutting made around 1936 its motor to drive shaft then shaft to pully to chuck

motor that came off origanaly was 3/4 hp ran ok till it went bang

checked bob weights and runnig free

thanks martin

Ian S C25/07/2014 13:00:56
7468 forum posts
230 photos

I imagine that it is a 4 pole, 1450 rpm motor, the normal for machinery, can't really give any further help there, but if it by chance it is a 2 pole 2800 rpm motor, what ever you do you will have trouble starting with a load, as the revs go up the torque goes down, double the revs, halve the torque. Ian S C

martin cropper25/07/2014 19:26:21
9 forum posts

thanks ian i dont knowif its 4 pole or 2

how do i tell

thanks martin

Frank.N Storm25/07/2014 20:03:15
48 forum posts
1 photos
Posted by martin cropper on 25/07/2014 19:26:21:

thanks ian i dont knowif its 4 pole or 2

how do i tell

thanks martin

If you would read Ian's answer (again), you wouldn't have to ask... cheeky

Regards, Frank

martin cropper26/07/2014 11:06:52
9 forum posts

thanks frank

i asume its 2 pole as for it starting is that what i missed in ians post

thanks again to all for your help tho

thanks martin

Phil Whitley26/07/2014 12:53:50
1394 forum posts
147 photos

the number of poles is directly related to the speed, which is a function of the frequency of the supply.. In a full cycle a 2 pole motor will make one revolution per cycle so 50 x 60seconds is 3000 rpm, knock off a bit for various losses and you get an average speed of about 2850 rpm. A 4 pole motor will make 1/2 a revolution per cycle so the speed will be a theoretical 1500 rpm, which usually averages out at about 1440 rpm, the most common speed. If your motor is running at 1440 (check the rating plate on the motor) it is a 4 pole. The rotor moves one pole for every completed cycle of the supply. less the "slip" the formula is 120 x frequency over number of poles. The centrifugal switch switches off the start winding when the motor is up to full speed, if the switch was stuck in the on position it is possible that the start winding is burnt out.

martin cropper26/07/2014 18:10:38
9 forum posts

thanks phili understand it a bit better now

the plates not that visable so couldent see any ratings

so would it be better to replace with a 4 pole motor

as to give more torq when starting the lathe which is direct drive no clutch

but thanks again for your advice

thanks martin yes

Edited By martin cropper on 26/07/2014 18:11:10

Phil Whitley26/07/2014 21:12:39
1394 forum posts
147 photos

Without seeing the lathe I couldnt tell, but if it is a Brooke Crompton 1 hp single phase the chances are it is a 1440 rpm, and doubling the speed most certainly won't do the lathe any good, and could overspeed and burst the chuck! More poles does not neccasarily mean more torque. Can you send a pic of the IXL lathe, I have had a look on google images, and they mostly look like they need a 2 to 3 hp motor... Do you have the countershaft with the fast and loose pulley as described on this page: If you do you should be starting the lathe with the belt on the loose pulley so that the notor gets up to speed before you put load on it. If the centrifugal switch is now working and it still blows fuses there is a fault somewhere, unless it is starting into a load it can't handle. Try starting with the belt on a different speed position. Has this motor worked ok on this lathe before, and the fault has just occured, or has the motor just been fitted?


martin cropper26/07/2014 21:31:46
9 forum posts

hi phil no its a other motor my lathe is the same one on the link you sent me on lathes

it the bottem blue one except mine has no longer on fast and loose

its been converted to pullys and the motor fixed at the back

it has forward and reverse on the apron travel

and tumbler reverse and cross slide drive

the old motor was 3/4 hp

and started it no probs but was from the 60,s i think and had a wobbler

hense the change i will try put some photos on

but same as the blue / green one at bottom of page

i start it in free mode if you like with nothing else engaged if that makes sense

i have tryed starting on another setting there are 3 same as other but pulley drive

starts ok with bigger fuse but blows smaller one

i think probably a brand new motor and switch

thanks again martin

Edited By martin cropper on 26/07/2014 21:32:32

mechman4815/07/2017 19:45:33
2938 forum posts
466 photos

Help needed for bench drill motor; I have a Clarke metalworker bench drill that up until today was working ok. this afternoon I went into my man cave to potter on something & when I came to use the bench drill it started buzzing when I switched it on & wouldn't start up properly i.e. wouldn't rotate immediately as it did previously. The only way it starts up is if I give the chuck a helping hand to start rotation then it runs ok. I took the belt off, the motor rotates fine, no rumble on the bearings when switched on, the spindle is as free as it was the other day no binding on that but as soon as the belt is replaced the motor buzzes ( loaded ) & struggles to start without my assistance. I suspect this is the motor telling me 'I'm giving up soon'. Has a winding gone down, is the capacitor defunct... There is no magic smoke & no burning smell... yet! apart from simple wiring up a socket, household stuff, & aware of Ohms Law etc I am totally non compos mentis re electrikery

​Considering the type of drill it is, from MM ( usual disc' ), I suspect it will be cheaper to by a new drill than to buy a new motor or have the motor checked out can anyone offer hope... advice... there are a couple of days left on MM's vat free offer this week so I have to make some decision over the next day or two.



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